This invention relates to an apparatus and method for dispensing a fluent material to pouches and, more particularly, to a method and apparatus for continuously filling successive pouches with an accurately measured mass of material whereby filled pouches are produced having a minimum amount of variation in weight.
The present invention further relates to filling and sealing a series of pouches or bags formed of plastic or other material, such as plastic foil laminates, on a continuous basis, and it has particular relation to machines and methods of the type shown in U.S. Pat. Nos. 3,813,845, 4,021,283, 4,171,604 and 4,893,453, which patents are co-owned by Weikert.
In the apparatus disclosed in the above-noted patents, a tube of material is first divided into a series of contiguous bags or pouches sealed from each other along their adjacent sides but interconnected through a continuous tubular portion which initially forms a common top for all of the bags or pouches. The tubular portion of this web is drawn along an elongated filling pipe having discharge ports at one end from which material is poured into each successive bag, with this processing line being tilted upwardly so that excess material in one bag will spill over into the adjacent following bag. After each bag is filled, it is sealed across the top and severed from the tubular portion as a separate, filled and sealed package. One problem associated with this filling system results from residual product coating the inner upper sides of the pouches as product flows from one pouch to a following pouch, which can interfere with a proper seal being formed at the top of the pouches.
While the apparatus and methods disclosed in the above-noted patents have proven successful for their intended purpose of successively filling pouches under aseptic conditions, the prior art apparatus and methods rely largely upon the physical characteristics of the pouches being filled and/or controlled opening and closing of dispensing ports, as well as the speed of the pouches as they are conveyed along the filling pipe, in order to ensure that a consistent mass or weight of material is packaged within each of the pouches. For example, the apparatus disclosed in U.S. Pat. No. 4,893,453 includes a shuttle plate to control filling through two apertures. The shuttle plate is actuated by an air cylinder operating under control of an electrosolenoid, and actuation occurs in response to a photocell sensor sensing the separation between pouches. However, the pouches are flexible such that a certain amount of deviation occurs in the sensed spacing between pouches, and operation of the shuttle plate based solely on the sensing of the pouches has therefore resulted in variations in the uniformity of the pouch content weight.
Consequently, there is a need for a packaging apparatus and method whereby a fluent material may be aseptically packaged in successive pouches and wherein there is very little variation in the mass or weight from pouch to pouch.